The Linux on iPod developer blog says the 5.5g iPods can now run Linux –

Many thanks and cheers to the hard work by DataGhost et al. in figuring out all of the final little bits in getting 5.5th gen iPods working with iPod Linux (Winpods and Macpods, 30 and 80 gig units). His various patches have been checked in, and integrated into the current nightly build of the kernel.

There’s a minor patch being integrated today that will allow 30 gig units to work properly… look for that kernel tomorrow!

More information can be found on the 5.5G Wiki Page with respect to installing these experimental builds on your 5.5th gen iPod.